Iterables.addAll(queue, elements);
    return queue;
  }

  // SynchronousQueue

  /** Creates an empty {@code SynchronousQueue} with nonfair access policy. */
  @J2ktIncompatible
  @GwtIncompatible // SynchronousQueue
  public static <E> SynchronousQueue<E> newSynchronousQueue() {
    return new SynchronousQueue<>();
  }

  /**

import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests for {@link Queues}.
 *
 * @author Dimitris Andreou
 */

import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests for {@link Queues}.
 *
 * @author Dimitris Andreou
 */

import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;